Fix Bug 1455081 - update icon and text tertiary colors in dark theme
Fix Bug 1455081 - update icon and text tertiary colors in dark theme

Mardak/activity-stream,AdamHillier/activity-stream,mozilla/activity-streams,rlr/activity-streams,mozilla/activity-streams,AdamHillier/activity-stream,sarracini/activity-stream,Mardak/activity-stream,sarracini/activity-stream,sarracini/activity-stream,mozilla/activity-stream,Mardak/activity-stream,AdamHillier/activity-stream,mozilla/activity-stream,AdamHillier/activity-stream,rlr/activity-streams,mozilla/activity-stream,rlr/activity-streams,Mardak/activity-stream,sarracini/activity-stream,rlr/activity-streams,mozilla/activity-stream